判断回文数字

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• Ppalindrome Number
  Determine whether an integer is a palindrome. Do this without extra space.
  Some hints:
  Could negative integers be palindromes? (ie, -1)
  If yu are thinking of converting the integer to string, note the restriction of using extra space.
  You could also try reversing an integer. However, if you have solved the problem "Reverse Integer", you know that the reversed integer might overflow. How would you handle such case?
  There is a more generic way of solving this problem.
• 题目大意：判断一个整数是否是回文数字，不要使用额外的空间。
• 思路：反转这个整数，看与原来的数字是否相等。
• 代码：

#include<iostream>
using namespace std;
// 方法一
bool isPalindrome(int x)
{
    if(x<0 || x%10==0&&x!=0)return false;
    long y = x;
    long temp=0;
    while(y>0)
    {
        temp = temp*10+y%10;
        y/=10;
    }
    return temp==x;
}
int main()
{
    int x;
    cin>>x;
    if(isPalindrome(x))
    {
        cout<<"是回文数字"<<endl;
    }
    else
    {
        cout<<"不是回文数字"<<endl;
    }
    return 0;
}

    //方法二
    bool isPalindrome(int x)
    {
        if(x<0)return false;
        char ch[100];
        int k=0;
        while(x>0)
        {
            ch[k++] = char(x%10+'0');
            x/=10;
        }
        ch[k]='\0';
        k--;
        for(int i=0;i<k;i++,k--)
        {
            if(ch[i]!=ch[k])return false;
        }
        return true;
    }

• 以上。

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欢迎来踩~~~~